The present invention relates to an apparatus and a method for filtering sectioning wastes of a microtome that are present in an air stream. The apparatus encompasses an aspiration device. With the aspiration device, sectioning waste can be aspirated from the blade region of the microtome with an air stream. The aspiration device comprises a main filter in which the sectioning wastes can be filtered from the air. The present invention further relates to a microtome.
Microtomes are known from the existing art, for example from DE 103 52 578 B3, and are used predominantly for the production of thin paraffin sections in the field of biology, medicine, and industrial research. The histological sample, tissue sample, or preparation to be investigated is usually, in a preceding preparation process, embedded in an embedding medium, for example in paraffin, thereby forming a block. The cross section of the block is usually rectangular, but can also be round and in particular of circular configuration. The block is usually mounted on a part of a cassette, in which the tissue sample is located in the preceding preparation process. With this part of the cassette, the block is clamped into a specimen holding device of the microtome. For sectioning, a drive device is provided that guides the sample or block located in the specimen holding device, by means of a relative motion, over a knife arranged on the microtome. The knife is generally horizontally displaceable in a knife holding device, and can be clamped in at an adjustable angle in defined fashion.
For production of an optimum section surface of a block, the microtome can have a trimming function. For that purpose, the knife holding device can be directed manually via a trimming lever toward the vertically movable specimen holding apparatus for initial sectioning operations, in steps that are larger as compared with the actual sectioning thickness. An unusable sectioning waste is produced in this operation, and collects e.g. in a section collection pan of the microtome.
In histology in particular, the specimens to be investigated often involve contaminated or bacterially affected biological material that can be mixed with paraffin from the preparation process. Even when the samples are sectioned correctly with the microtome, a fine sectioning waste unavoidably occurs; this falls down from the microtome knife and is deposited onto parts of the microtome located therebeneath, for example its housing parts, and in particular in open gaps and especially in the section collection pan. Provision can therefore be made for the sectioning waste produced at the blade region of the microtome to be aspirated with the aid of an aspiration device. This is used in particular with cryostat microtomes, as disclosed, for example, in EP 0 725 712 B1. The aspiration device disclosed therein encompasses a main filter in which the sectioning wastes can be filtered out of the air. In other words, the sectioning wastes are retained in the main filter and separated from the air transporting the sectioning wastes. If, for example during the trimming operation, an important part of the sample (or the entire sample) is then inadvertently cut off and aspirated by the aspiration device, the possibility exists of retrieving that section by looking for the corresponding section in the main filter. Confusion can arise in this context, however, with sections from other samples and thus, in some circumstances, from other patients; this must be avoided.